httprepo: suppress the `real URL is...' message in safe, common cases.
When the actual and requested URL only differ by trailing slashes,
there is no need to warn. As an example, this easily happens when
accessing repositories on Bitbucket over HTTP(S).
As far as I could tell, there were no existing tests for this
behaviour.
adding file
% create a second head
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
created new head
% failing merge
0 files updated, 0 files merged, 0 files removed, 1 files unresolved
use 'hg resolve' to retry unresolved file merges or 'hg update -C' to abandon
% resolve -l, should be empty